Philadelphia, Pennsylvania - In one of the oldest unsolved murder cases in the history of Philadelphia, law enforcement has made what appears to be a decisive advance after more than 65 years.

Police identified the child's body, found in 1957, as that of Joseph Augustus Zarelli, officials said. Known as the "boy in a cardboard box," the case came to light when Zarelli was found in a cardboard box in what was then a rural area outside Philadelphia.

DNA analysis put investigators on the trail of the boy's identity, which had tracked down relatives of the previously unnamed boy and also found a birth certificate, they said.

The family was from West Philadelphia, and Zarelli was born on January 13, 1953.

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Both parents are now dead, but a number of siblings are still alive.

Investigator John Smith said there is a guess as to who the perpetrator or perpetrator might be, but did not initially give details. Although so many years have passed, murder charges could still be filed in this cold case.

The unclothed body of the four-year-old boy was wrapped in a blanket and showed signs of numerous blows when it was found more than 65 years ago. "Cause of death was blunt force trauma," a now-retired investigator had told the CBS station in 2021.

In addition, the victim had been washed and had had his hair cut.

The investigation, which dragged on for years, brought no breakthrough. At that time, sheets with the face of the blond boy had been distributed throughout the city to ask the population for help.

The child also became known as "America's Unknown Child" per the late boy's headstone in Philadelphia's Ivy Hill Cemetery, where the remains were last exhumed in 2019 to collect DNA samples, according to reports.